This invention is related to a magnifying apparatus, and more particularly, to an apparatus and method used to view an object such as a book or other printed material on a surface by magnifying the image of the object and viewing the magnified image at a convenient angle to the surface on which the object is located. Specifically, this invention is related to the use of fiber optic tapers as magnifiers. Stand magnifiers are frequently used as a visual aid by the visually impaired. Their main advantage over other reading aids is their relative stability and ease of use. The fixed and stable distance from the reading material, and the flexibility in distance from the eye to the magnifier make their use easy to learn.
Most existing stand magnifiers, however, require the user to bend over the magnifier in order to be able to read through them. When used at a desk, for example, the user has to lean forward and closely follow, with his/her whole upper-body, the position of the magnifier on the page.
The postural problem with the stand magnifier also complicates the attainment of proper illumination for the printed material. The user's head tends to block light from above, and thus the need to permit light access through the sides of the magnifier which makes for an uncomfortable and difficult hand grip. The difficulties in getting proper illumination have resulted in the development of many electrically powered illuminated stand magnifiers. As one solution to these difficulties, Combined Optical Industries Limited (COIL), 200 Bath Road, Slough, SL14DW, England, has recently introduced a series of tilting stand magnifiers (Coil 5214). However, tilting the lens results in distortions and reduces the field of view. U.S. Pat. No. 4,923,282 (Spitzberg-et al.) discloses another attempt to address this issue with a design that incorporates a prism to tilt the image's angle.
As with all other lens magnifiers, the stand magnifiers are limited also by distortions and vignetting. In most cases, the limited field prevents binocular use and thus eliminates the potential benefits of binocular vision. Attempts to increase the field by aspheric lens design usually further increase the optical distortions.
The actual magnification provided by lens magnifiers is not easily defined or measured. The information provided by the manufacturer is frequently inaccurate and misleading (Bullimore and Bailey, Stand magnifiers: an evaluation of new optical aids from COIL, Optometry and Vision Science, 66; 766-773, 1989), thus making the use and prescription of these devices unnecessarily complicated.
As an entirely different approach a symmetrical bundle of tapered optical fibers (commonly referred to as a taper) such as that shown in FIG. 1 has been used as a magnifier. The most common application has been for use by stamp collectors. The image light from these magnifiers is directed for the most part perpendicular to the viewing face making the best viewing position directly over the magnifier. While a user may tolerate bending over the magnifier to view a stamp, it would be very awkward for extended use in reading a book, for example. Furthermore, these symmetrical optical fiber tapers provide no control over unwanted specular reflection.
There is, therefore, a need for a magnifier which does not introduce distortion and which can be used by a person sitting in an upright position, and which does not require the person to bend over the apparatus when reading a full page of text.